A marilith usually holds a longsword in each of its six hands and wears many bangles and jewels.

A marilith stands about 9 feet tall and measures about 20 feet from head to tip of tail. It weighs about 4,000 pounds.

Combat

Though mariliths thrive on grand strategy and army-level tactics, they love physical combat and never pass up an opportunity to fight. Each of a marilith’s six arms can wield a weapon, and the creature gets an additional three weapon attacks with its primary arm. Mariliths seldom rush headlong into battle, however, preferring to hang back and size up the situation first. They always seek to gain the best possible advantage from the local terrain, obstacles, and any vulnerability or weakness in their opponents.

A marilith’s natural weapons, as well as any weapons it wields, are treated as chaotic-aligned and evil-aligned for the purpose of overcoming damage reduction.

Extraordinary Ability(Ex)

Constrict (Ex)
A marilith deals 4d6+13 points of damage with a successful grapple check. The constricted creature must succeed on a DC 27 Fortitude save or lose consciousness for as long as it remains in the coils and for 2d4 rounds thereafter. The save DC is Strength-based.

Improved Grab (Ex)
To use this ability, a marilith must hit with its tail slap attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it succeeds on the grapple check, it can constrict.

Summon Demon (Sp)
Once per day a marilith can attempt to summon 4d10 dretches, 1d4 hezrou, or one nalfeshnee with a 50% chance of success, or one glabrezu or another marilith with a 20% chance of success. This ability is the equivalent of a 5th-level spell.

Feats
In combination with its natural abilities, a marilith’s Multiweapon Fighting feat allows it to attack with all its arms at no penalty.

Possessions

Research

Item I

Defending
A defending weapon allows the wielder to transfer some or all of the sword’s enhancement bonus to his AC as a bonus that stacks with all others. As a free action, the wielder chooses how to allocate the weapon’s enhancement bonus at the start of his turn before using the weapon, and the effect to AC lasts until his next turn.

Penalties for fighting with multiple weapons are reduced by 2 with the primary hand and reduced by 6 with off hands.

In addition to the single extra attack a creature gets with each extra weapon from Multiweapon Fighting, it gets a second attack with each extra weapon, albeit at a -5 penalty.

The creature may make up to three extra attacks with each extra offhand weapon it wields, albeit at a -10 penalty on the third attack with each weapon.

Special
This Feat Line replaces the Two-weapon Fighting Line for creatures with more than two arms.

Item III

Haste

Item IV

Flurry of Blows (Ex)
When unarmored, a monk may strike with a flurry of blows at the expense of accuracy. When doing so, she may make one extra attack in a round at her highest base attack bonus, but this attack takes a -2 penalty, as does each other attack made that round. The resulting modified base attack bonuses are shown in the Flurry of Blows Attack Bonus column on Table: The Monk. This penalty applies for 1 round, so it also affects attacks of opportunity the monk might make before her next action...

When using flurry of blows, a monk may attack only with unarmed strikes or with special monk weapons (kama, nunchaku, quarterstaff, sai, shuriken, and siangham). She may attack with unarmed strikes and special monk weapons interchangeably as desired. When using weapons as part of a flurry of blows, a monk applies her Strength bonus (not Str bonus × 1˝ or ×˝) to her damage rolls for all successful attacks, whether she wields a weapon in one or both hands. The monk can’t use any weapon other than a special monk weapon as part of a flurry of blows.

Item V

Esoteric Weapon Training [Fighter, General]Your monastic training includes practice with an unusual weapon, one not commonly found among monastic ordersPrerequisite Flurry of Blows class abilityBenefit Select a one-handed, light, or ranged weapon that requires martial weapon proficiency, or any simple weapon. You gain proficiency with this weapon, and it is considered a special monk weapon for you and may perform Flurry or Decisive Strikes with it.SpecialIf you have the Moment of Perfection class feature, you gain the following ability: Expend a use of Moment of Perfection and perform a flurry with the selected weapon: Every attack roll you make as part of the flurry adds the insight bonus from Moment of Perfection and ignores concealment and total concealment (although you must still target the right square).
A fighter may select this Feat as one of his fighter bonus feats.
Source: The Jiriku Monk Remix

When unarmored, a monk may strike ... at the expense of accuracy. When doing so, she may make [0 to 3] extra attack[s] in a round at her highest base attack bonus, but [these attacks take] a -2 penalty, as does each other attack made that round.

This tanar'ri marilith holds a longsword in each of its six hands with the tell-tale sign of thousands of years of mastery. Long hair, with bangles, and charms, the color of the setting sun falls down her back, a bright ted tunic, embued with leeching magic wrapped around her upper-body in tight bands.
The marilith is an unparralleled expert with its blades, and over the next few thousand years...
...it intends to become a true master.
A marilith stands about 9 feet tall and measures about 20 feet from head to tip of tail. It weighs about 4,000 pounds.

Combat

Though mariliths thrive on grand strategy and army-level tactics, they love physical combat and never pass up an opportunity to fight. Each of a marilith’s six arms can wield a weapon, and the creature gets an additional three weapon attacks with its primary arm. Mariliths seldom rush headlong into battle, however, preferring to hang back and size up the situation first. They always seek to gain the best possible advantage from the local terrain, obstacles, and any vulnerability or weakness in their opponents.

A marilith’s natural weapons, as well as any weapons it wields, are treated as chaotic-aligned and evil-aligned for the purpose of overcoming damage reduction.

The tanar'ri marilith wades into battle, trying to bring as many of its attacks to bear on as many opponents as possible.
Relying on its aura of legacy, and monk-derived defenses, its shirt of the leech, allows it to benefit from its enemies healing and provides extra protection in the way of powerful abjurations.
In the midst of combat, it lashes out with flailing strikes, never retreating and severely punishing anything that breaks its barrier. Its unique style forces others to think twice before attacking, while punishing those who approach, yet hesitate.
If denied its precious longsword, the tanari'ri marilith has no fear of going hand to...
...tail, looping and crushing its opponents in lethal grapples.
Yet even as its weapons are reduced, it will simply switch to two-handed strikes, thus dealing out more damage.
By dint of its helm, the tanar'ri marilith has speed to act first in combat, and protection from mental interference.

Smite Good (Su)
Once per day a tanar'ri can make a normal melee attack to deal extra damage equal to its HD total (maximum of +20) against a good foe.

See in Darkness (Su)
A tanar'ri see perfectly in darkness of any kind, even that created by a deeper darkness spell.

Tongues (Su)
A tanar'ri can speak with any creature that has a language, as though using a tongues spell (caster level 21). This ability is always active.

Aura of Legacy (Su)
Against attacks made or effects created by a tanar'ri's enemies, this ability provides a +2 deflection bonus to AC and a +2 resistance bonus on saving throws to anyone within 20 feet of the tanar'ri's. All enemies take a -2 penalty to all rolls, saves and checks within 20 ft of the tanar'ri. Otherwise, it functions as a unholy aura effect and a lesser globe of invulnerability, both with a radius of 20 feet (caster level equals tanar'ri's HD). This aura can be dispelled, but the tanar'ri can create it again as a free action on its next turn. (The defensive benefits from the circle are not included in an tanar'ri’s statistics block.)

Constrict (Ex)
A marilith deals 6d6+13 points of damage with a successful grapple check. The constricted creature must succeed on a DC 33 Fortitude save or lose consciousness for as long as it remains in the coils and for 2d6 rounds thereafter. The save DC is Strength-based.

Improved Grab (Ex)
To use this ability, a marilith must hit with its tail slap attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it succeeds on the grapple check, it can constrict.

Flailing Strike
Rolls a 1d4-1, and makes that number of extra attacks on a full-attack, with a -2 penalty to all.Source: Dragon 355, Page 89

Decisive Strike
As a full-round action, make one attack with an unarmed strike or a special monk weapon, using your highest base attack bonus but taking a –2 penalty on this attack roll. If the attack hits, it deals double damage (as does any other attack you make before the start of your next turn). If you use this strike to deliver a stunning attack, increase the save DC to resist the stun by 2. This is an extraordinary ability.Source: PHB II

Summon Demon(Sp)
Once per day a marilith can attempt to summon 4d10 dretches, 1d4 hezrou, or one nalfeshnee with a 50% chance of success, or one glabrezu or another marilith with a 20% chance of success. This ability is the equivalent of a 5th-level spell.

True Seeing(Su)
Mariliths continuously use this ability, as the spell (caster level 16th).

Weapon Focus Path
Effects are multiplied by 5, for a net result of +20 to attack rolls, and +40 to damage rolls. Actual feats are multiplied by six, for a net result of +24 to attack rolls and +48 to damage rolls.

Combat Reflexes
You may make a number of additional attacks of opportunity equal to your Dexterity bonus.
With this feat, you may also make attacks of opportunity while flat-footed.Source: SRD

Melee Weapon Mastery
When you select this feat, choose bludgeoning, piercing, or slashing. You must have Weapon Focus and Weapon Specialization with a melee weapon that deals this type of damage. When using any melee weapon that has the damage type you selected, you gain a +2 bonus on attack rolls and a +2 bonus on damage rolls.Source: PHB II

Multiweapon Rend
If you hit an opponent with two or more weapons (wielded in different hands) in the same round, you may automatically rend the opponent. This rending deals additional damage equal to the base damage of the smallest weapon that hit plus 1 ˝ times your Strength modifier. You can only rend once per round, regardless of how many successful attacks you make. Source: SRD

Slashing Flurry
When you use a standard action to attack with any slashing weapon, you can choose to make a second attack
with that weapon. You take a –5 penalty on the first attack, and a –10 penalty on the second.
When you use a full attack action with any slashing weapon, you gain one additional attack at your highest base
attack bonus. That attack and all other attacks you make in the current round take a –5 penalty.Source: PHB II

Overwhelming Assault
As a free action, designate one specific foe as the target of this feat. If this foe begins his turn adjacent to you, ends his turn still adjacent to you, and does not attack you, target you with a spell, or use a special ability against you, you gain a +4 bonus on melee attack rolls against him on your next turn.Source: PHB II

Improved Combat Expertise
When you use the attack action or the full attack action in melee, you can take a penalty of as much as -5 on your attack roll and add the same number (+5 or less) as a dodge bonus to your Armor Class. This number may not exceed your base attack bonus. The changes to attack rolls and Armor Class last until your next action.
When you use the Combat Expertise feat to improve your Armor Class, the number you subtract from your attack roll and add to your AC can be any number that does not exceed your base attack bonus.Source: CW

Multiattack
The creature’s secondary attacks with natural weapons take only a -2 penalty.
Without this feat, the creature’s secondary attacks with natural weapons take a -5 penalty.Source: SRD

Power Attack
+3 bonus on her melee damage rolls for every –2 penalty they take on their melee attack rolls when using the Power Attack feat (or +3 for every –1 penalty if wielding a two-handed weapon other than a double weapon). This benefit does not stack with the normal effects of Power Attack.Source: SRD

Dodge
During your action, you designate an opponent and receive a +1 dodge bonus to Armor Class against attacks from that opponent. You can select a new opponent on any action.
A condition that makes you lose your Dexterity bonus to Armor Class (if any) also makes you lose dodge bonuses. Also, dodge bonuses stack with each other, unlike most other types of bonuses. Source: SRD

Naturalized Denizen
You are never treated as an extraplanar creature (and you lose the extraplanar subtype). Thus, you can't be affected by a banishment or dismissal spell or similar effects that send extraplanar creatures back to their home planes.Source: SRD: UA

Esoteric Weapon Training
You gain proficiency with this weapon, and it is considered a special monk weapon for you and may perform Flurry or Decisive Strikes with it.

Robilar's Gambit
At the start of your action, you can adopt a fighting stance that exposes you to harm but allows you to take advantage of your opponents’ exposed defenses as they reach in to attack you. Anyone who strikes at you gains a +4 bonus on attack rolls and damage rolls against you. In return, they provoke attacks of opportunity from you each time they swing. Resolve your attack of opportunity after your foe’s attack.Source: PHB II

Improved Grapple
You do not provoke an attack of opportunity when you make a touch attack to start a grapple. You also gain a +4 bonus on all grapple checks, regardless of whether you started the grapple.Source: SRD

Greater Multiweapon Fighting
In addition to the single extra attack a creature gets with each extra weapon from Multiweapon Fighting, it gets a second attack with each extra weapon, albeit at a -5 penalty.Source: SRD

Grudge Keeper[FLAW]
When damaged in combat you suffer a -2 on attack rolls, skill checks, saving throws and ability checks until you damage the foe that caused you harm. Doesn’t apply if you cannot discern the source of the damage. This penalty disappears after the combat ends.Source

Implacable[FLAW]
If you move out of melee combat, for any reason, you suffer a -2 on al attack rolls, skill checks and saving throws for 1 hour.Source

Shirt of the Leech(continuous)
Whenever a healing spell of 4th level or lower is cast within 30 feet of you, you instantly recognize the spell being cast.
This is a continuous effect and requires no activation.
As an immediate action, you can activate a shirt of the leech to gain the effect of any healing spell cast within 30 feet of you,
instead of the spell affecting its intended target. If the spell would normally affect more than one creature, you choose which
target does not gain the effect. You must have line of sight to both the caster and the target to use this effect.This ability functions three times per day.
This ability is usable at-will, once per round.Source: MIC

Helm of Righteous War and Mental Fortitude
The helm of righteous war grants you a +2 insight bonus on initiative checks and Spot checks. This helmet protects the wearer against all mindaffecting spells and abilities as long as it is worn. She need not make any saving throws against these effects; they simply fail to affect her.
The bumpy, ridged surface of this platinum helm is disturbingly reminiscent of a brain. Small flakes of gold lie within some of the cracks, as if protecting the “brain” from intrusion.
When the wearer is subjected to a mind-affecting spell or ability, the helm glows with a dim, gray light.
This visible signal that a mind-affecting attack has been directed at the wearer is enough to make adventurers prize this ring.Source: MIC & DMG II

Skills
Mariliths have a +8 racial bonus on Listen and Spot checks.

Feats
In combination with its natural abilities, a marilith’s Multiweapon Fighting feat allows it to attack with all its arms at no penalty.